Technical Field
The technical field relates generally to state control of electrical power distribution systems on motor vehicles, and more particularly, to a state control system for a high voltage power distribution system which anticipates operator operational demands based on driver location in the motor vehicle, driver movement proximate to the motor vehicle and location of the motor vehicle.
Description of the Technical Field
Electric and hybrid vehicles, particularly hybrid-electric vehicles, are increasingly common, particularly for buses and for commuter and urban delivery applications. The electrical power distribution systems for these vehicles usually include more than one high voltage electric power distribution sub-systems because, in part, high voltage power distribution reduces current losses. The power distribution sub-systems may operate at different nominal voltage levels and both direct current (DC) or alternating current (AC) sub-systems may be present.
Power is supplied to the high voltage electric power distribution sub-systems from the vehicle's rechargeable energy storage system (RESS). For an electric vehicle the RESS is the exclusive source of power during vehicle operation. The RESS is usually a substantial battery system, though it may be constructed in alternative forms, such as capacitors or even fuel cells. Contemporary RESS units, particularly those constructed from batteries, tend to exhibit a relatively low density energy storage in comparison to fossil fuels, and as a consequence, the all electric range of electric and hybrid vehicles is usually substantially less than it is for vehicles which burn fossil fuels.
Specialized switching devices such as contactors are used to control connection of the RESS to the high voltage electric power distribution sub-systems. Because closure of the contactors can produce a large current inrush to previously unenergized high voltage sub-systems, the power distribution system will often include a pre-charge resistor system. A plurality of contactors are provided which allow current to be routed through the pre-charge resistors to prevent an initial current surge from the RESS and to bypass the pre-charge resistors to reduce losses during operation. In this way initial power flow on power up is limited. The process of powering up can, however, take an appreciable amount of time to carry out.
Contemporary vehicles use distributed computer control over vehicle systems. This includes control over electrical power distribution. Distributed control includes system specific controllers such as: transmission controllers, engine controllers and motor controllers associated with the drive train; ancillary controllers such as used for power steering motors and the like; and, battery management systems associated with the RESS. The controllers are linked by wiring or optical cable for the exchange of data. The linkage is commonly operated in what is termed a controller area network (CAN) with the controllers providing network nodes. The network nodes/controllers are computers and thus they consume power. They also take appreciable time to boot up and shut down.
Keeping a power distribution system in a state of full readiness can be a substantial power drain on the RESS. Good energy management of the RESS calls for minimizing energy/power drains on the RESS to increase vehicle range. This in turn suggests that vehicle electric power distribution sub-systems could be powered down when not in use to avoid a drain on the RESS. The time taken to shut down and energize the power distribution sub-systems and to boot up on board computer are practical limitations on taking such steps, particularly on a vehicle used for small package delivery.